A valve seat grinding apparatus is disclosed in U.S. Pat. No. 4,287,688. As disclosed, the present invention is a combination of the kind as disclosed in this patent and, accordingly, the patent is hereby incorporated by reference. The commonly owned and copending U.S. application Ser. No. 650,841, filed Sept. 17, 1984 now U.S. Pat. No. 4,610,112, has of record the presently known prior art pertaining to valve grinding apparatus, including German GM No. 8303975 (1983). Also of record in this referenced application is Ser. No. 705,869, filed Feb. 28, 1985, which has been allowed. The flexible shaft torque transfer coupler disclosed herein may be a coupler as disclosed in either of the above referenced U.S. or German patents, or a modification of the coupler disclosed in the commonly owned and copending U.S. application Ser. No. 843,292, filed Mar. 24, 1986, and entitled "Improved Valve Seat Grinding Apparatus".